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Monday, March 28, 2011

Will we hear the light?

Using an elaborate apparatus to study the inner-ear cells of the oyster toadfish (in clear plastic container, lower right), University of Utah bioengineering professor Richard Rabbitt found that infrared light similar to those in laser pointers -- but at a longer and invisible wavelength -- can make inner-ear "hair cells" send signals to adjacent nerve cells and then to the brain.

Lee Siegel - University of Utah scientists used invisible infrared light to make rat heart cells contract and toadfish inner-ear cells send signals to the brain. The discovery someday might improve cochlear implants for deafness and lead to devices to restore vision, maintain balance and treat movement disorders like Parkinson's.

"We're going to talk to the brain with optical infrared pulses instead of electrical pulses," which now are used in cochlear implants to provide deaf people with limited hearing, says Richard Rabbitt, a professor of bioengineering and senior author of the heart-cell and inner-ear-cell studies published this month in The Journal of Physiology.

The studies – funded by the National Institutes of Health – also raise the possibility of developing cardiac pacemakers that use optical signals rather than electrical signals to stimulate heart cells. But Rabbitt says that because electronic pacemakers work well, "I don't see a market for an optical pacemaker at the present time."

The scientific significance of the studies is the discovery that optical signals – short pulses of an invisible wavelength of infrared laser light delivered via a thin, glass optical fiber – can activate heart cells and inner-ear cells related to balance and hearing.

In addition, the research showed infrared activates the heart cells, called cardiomyocytes, by triggering the movement of calcium ions in and out of mitochondria, the organelles or components within cells that convert sugar into usable energy. The same process appears to occur when infrared light stimulates inner-ear cells.

Infrared light can be felt as heat, raising the possibility the heart and ear cells were activated by heat rather than the infrared radiation itself. But Rabbitt and colleagues did "elegant experiments" to show the cells indeed were activated by the infrared radiation, says a commentary in the journal by Ian Curthoys of the University of Sydney, Australia.

Curthoys writes that the research provides "stunningly bright insight" into events within inner-ear cells and "has great potential for future clinical application." ...